1 - from the command line type:yum update glibcNOTE: After the update the appliance needs to be rebooted.
The OS will be updated and the vulnerability will be corrected.

2 - For system that do not have access to the internet there are 2 copies of glibc rpm (i686 and x86_64) and 1 dependent component - glibc-common - all 3 of these would need to be downloaded manually from this URL: http://mirror.centos.org/centos-5/5.11/updates/x86_64/RPMS/